Gibson 1937-1941 (1941) EH 150 Amplifier 3rd Series
The new EH-150 of 1937 was found in the pages of 1937's Catalog Y, above. The new 7 tube amp also featured a new look. Instead of the 4 sharp corners found on the earlier amps, the top corners were rounded and the top leather ends were eliminated. The inside brown crinckle lining was replaced with a light cream colored leatherette lining.
The inside components changed significantly. The speaker size increased from a 10" to a 12" field-coil with the Gibson name on the magnet cover.
According to 'Vintage Guitar Magazine',
'A beefed up circuit employing seven tubes featured the relatively new 6L6 beam-power variety, in metal. The 5Z3 rectifier, 6C5 driver and 6F5 microphone channel preamp remained from the earlier model, but the twin triode 6N7 was replaced with two 6C5 triodes for the instrument and microphone channels. Power ratings were given for the first time, a respectable 15 watts'.
This 3rd generation EH amp would be used from 1937 up until 1941/1942, when it would be changed briefly to the 4th variation. Interestingly, 1942's 4th version EH 150 shared the same circuit design and the Giant EH 185 model.
Label above is the Western Electric licensing agreement granted to Electrical Research Products, Inc., who also made amps for Oahu, Harmony, etc.